In the oil and gas industry, wellbores are commonly completed by cementing wellbore liner (e.g., casing, liner, etc.) into the drilled borehole. In some cementation operations, a wiper dart (alternately referred to as a dart, a wiper plug, a cementing plug, a drill pipe dart, and a drill pipe wiping dart) is pumped downhole to hydraulically force a cement slurry through the wellbore liner and out into the open wellbore. The cement slurry exits the wellbore liner and flows into an annulus defined between the wellbore liner and the wellbore wall where it eventually cures to provide a cement sheath that secures the wellbore liner within the wellbore.
Wiper darts are typically pumped downhole through a work string extended into the wellbore, including multiple lengths of drill pipe or other tubulars connected end to end. Wiper darts commonly have one or more wiper elements or “cups” that flare radially outward to sealingly engage the inner diameter of the work string. The wiper elements help generate a pressure differential across the wiper dart by preventing fluid flow across the wiper dart as it is pumped downhole. Moreover, the wiper elements also serve to “wipe” the inner wall of the work string and thereby substantially remove the cement slurry from the work string.
Wiper darts are often required to pass through varying inner diameters as they are pumped downhole. For instance, multiple tubing sizes are commonly used within the same work string, and each tubing size can exhibit a different inner diameter. Moreover, wiper darts are also often required to pass through minimum restrictions provided by various downhole tools, such as a cement head, safety valves, a crossover tool, diverter tools, liner hangers, liner plug assemblies, and other conventional wellbore cementing tools. Accordingly, not only does a wiper dart have to effectively seal and wipe a variety of inner diameters as it is pumped downhole, it must also successfully pass through various minimum restrictions while performing these vital functions. Such small inner diameters or restrictions are collectively referred to herein as “reduced diameter restrictions.” Due to the immense amount of friction caused by the wiper elements as they pass through reduced diameter restrictions, the wiper dart can become stuck and may not reach its final destination. As can be appreciated, retrieving a stuck wiper dart can be a costly and time-consuming operation.